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Don't know, it is a Hewlett-Packard digital multi-meter, model E2378A. I have had it at least 16 years, until now it has been in perfect agreement the digital thermostat in our house, and ice and boiling water. However checking it against the thermostat this time gave a discrepancy of about 3.89 deg. C., with the meter reading higher than the thermostat. This time I was in a hurry, and did not calibrate it against ice and boiling water as I usually do when testing a sensor.
If I assume that the thermometer is the one that is reading the full 3.89 deg. C too high, then the readings at 60 and 80 deg. C could be right, but the reading at 40 deg. C is still too low indicating to the computers that the engine is warmer than it really is, although the resistance is only off by about 10%. Of course if the thermometer is only off by, say, half of the discrepancy, then the ECT sensor looks like it is a little out of whack, but not as much as if the thermometer is exactly accurate.
Before you ask, I checked the ohmmeter function against two known resistances today, high precision (+/- 1%) non-inductive 300 watt, 8 ohm resistors, and it was exactly right on. I do have some other +/- 5% resistors of higher resistance I could check the readings in the 300 to 600 ohm range and around 1300 ohms with, but for now I trust the meter.
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1955 Human, Scott; 1991 745 Turbo, Brunhilde; 1990 745GL, Snuggle Bunny
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